Piston, ring, and ring expander



Aug. 29, 1939. C, F. JQHNSTQN 2,170,970

PISTON. RING, AND RING EXPANDER Filed lay 15, 1937 F1553; f/ fifa /za A:l INVENTOR Hgo/7 /0/7. BY

ATTORNEY.

Patented ug. 29, 1939 UNITED STATES lPATENT OFFICE 2,170,970 rrs'roN,RING, AND RING EXPANDER Charles F. Johnston, Oakland, Calif. ApplicationMay 15, 1937, serial No. 142,351

6 Claims.

The invention relates to pistons such as used in internal combustionengines and which may have incorporated therewith piston rings and ringexpander means.

An object of the invention is to provide in a piston, rings and expandercombination of the character described an improved form and constructionaffording a. greatly improved life of the expander.

Another object of the invention is to provide in a combination of thecharacter described for a material strengthening of the support for thefree ends of the ring accomplishing `a substantially completeelimination of so-called ring flutter or destructive vibration of thefree ends of the ring.

A further object of the invention is to provide l an improved ventilatedoil ring affording a highv ly efficient oil lcontrol and improved oilpassage constructions and being Aeffective to substantially eliminatethe possibility of vclogging ofthe oil passages by the accumulation ofcarbon deposits on the ring.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forthfin the following'description of the preferred form of the invention which is illustratedin the drawing accompanying and forming part of the specication. It isto be understood, however, that variations in the showing made by thesaid drawing and description may be adopted within the scope of theinvention as set forth in the claims.

Referring to said drawing:

Figure 1 is a plan sectional View of a piston, ring and ring expandercombination constructed in accordance with the present invention.

Figure 2 is ka fragmentary vertical sectional view of the combinationshown in Figure 1.

' Figure 3 is a View similar to Figure 2. but showing a differentsection of the ring and with the latter compressed in a cylinder.

Figure 4 is a vertical elevation of the combina tion illustrated inFigure 1. g,

Figure 5 is a fragmentary sectional view similar to Figure 2, butshowing a modified form of the invention.

, Figure 6 is a plan view of the expander illustrated in Figure 4.

Figure 7 is a fragmentary cross sectional view of the expanderillustrated in Figure `6 and is taken substantially on the plane of linel--l of` Figure 6.

Figure 8 is a fragmentary cross sectional view 55 of the expanderillustrated in Figure 6 and is' taken substantially upon the plane ofline 8 8 of Figure 6.

The invention, as illustrated in the accompanying drawing, consists of apiston 8 which is provided with a plurality of longitudinally spaced 5annular ring grooves 9 which are each adapted for the receipt of apiston ring II. In accordance with the present arrangement a springexpander member I2 is mounted in the ring groove 9 behind the ring II soas to engage between the 10 base I3 of the groove and the inner face I4of the ring to resiliently urge the latter to an outward expandedposition against the cylinder side wall with which the piston is used.The expander I2 is preferably constructed of an elonl5 gated strip ofresilient material which is bent into a generally annular slnuous formso as to occupy a minimum amount of space when compressed between thering and the base of the ring groove and yet provide a substantialamount 20 of resilience for urging the ring to an expanded position.

Heretoforeit has been the practice to engage the fiat sides of theexpander spring with corresponding iiat sides at the base of the ringgroove and at the inner face of the ring. As a result the spring, aftera relatively short length of time, Was Worn thin at its points ofcontact with the ringA and the groove base and after a short periodV ofuse the spring would fail. In accordance with the present invention andas a principal object thereof, I have so designed the form of the pistongroove and the spring and the ring so as to very greatly increase thelife of the spring. In the present showing this construction is such asto cause the engagement of the spring between the base of the ringgroove and the inner face of the ring exclusively at the side edges ofthe strip which comprises the spring so that the strip has its entirewidth disposed in the direction of wear as contrasted to the formerarrangement wherein only the relatively thin side wall of the strip wasin the direction of wear. In the form of the invention illustrated inFigures 1-4 the base I3 of the groove and the inner face I4 of the ringare 45 provided with recesses receding away from the spring so as toallow the entry of the spring into the recesses and the latter are soformed as to engage the spring exclusively at the top and bottom edges I6 and I1 of the spring. As will be 50 seen from Figures 1-4 the recessesin the base I3 and the ring side I4 each taper away from the spring I2,the recess in the groove base I3 consisting of a pair of tapered sidesI8 and I9 which extend from the upper and lower ring lands 2| 55 and 22of the groove, while the recess provided in the side I4 of the ringconsists of a pair of tapered sides 23 and 24 which, as in the case ofthe recessed sides I8 and I9, engage the expander spring exclusively atthe top and bottom sides I6 and I1 thereof. As another important featureof this construction, it will be noted that due to the sinuous orpolygonal shape of the expander spring, any wear of the side edges I6and I1 at the surfaces I8, |9, 23 and 24 allows the spring to work itsway further into the recesses and thereby increases the wearing area onthe spring. While the recesses are here shown tapered it will beunderstood that the same may be rounded or otherwise curved so as toexclusively engage the top and bottom surfaces of the spring. y In theform of the invention illustrated in Figures 5-8 the arrangement forproviding for the wear on the spring exclusively at the side edgesthereof is effected by the construction of the spring itself. As hereshown, a plurality of alternately spaced radially outwardly extendingand radially inwardly extending projections 2B and 21 are formed on thetop and bottom edges I6 and |1 of the ring I2 for engagement with thering groove base and the inner periphery of the ring respectively. Inthis manner the wear on the spring is confined to the projections 26 and21 rather than across the full width of the expander spring. Inaccordance with the spring here shown the projections 26 are bentoutwardly from the body of the strip forming the spring I2 at thecorners 28 of the polygon formed by the spring while the projections 21are pressed inwardly at an intermediate portion of the sides 29 of thepolygon intermediate the corners 28.

As another important feature of the present invention both of the springexpanders I2 and I2', illustrated in the accompanying drawing, arearranged in a sinuous or polygonal shape with the outstanding corners 28and the intermediate sides 29 which are engaged with the inner face ofthe ring and the base of the ring groove respectively. As will be seenparticularly from Figure 1, the sides 29 of the polygon aresubstantially tangential to the inscribed circle formed by the base ofthe ring groove in the piston and the free ends 3| and 32 of the springare' formed as abbreviated side portions which extend substantially tothe inscribed circle and are substantially tangential with respectthereto. This construction is of great importance in rendering uniformthe resilience of the expander around the periphery thereof andproviding a uniform support for the piston ring. As Will be seen fromFigure 1, the engagement of the free end portions 3| and 32 with thebase of the piston groove gives the adjacent corner portions 28 of thespring a double support against the base of the ring groove 9 at the endportions 3| and 32 and the other at the next adjacent side 29 to thecorners 28'. In assembling the ring I prefer to arrange the free endportions 3| and 32 of the spring opposite to the free ends 33 and 34 ofthe ring so as to afford these free ends of the ring a maximum supportand to securely hold the latter against destructive vibration orso-called "ring flutter". As will be further understood, the extensionof the free ends 3| and 32 of the spring substantially to and tangentialwith the base of the ring groove, causes these free end portions toconstantly hug the base of the ring groove in all positions of relativecompression of the spring and at no time is it possible for the freeends of the spring to Work or find their Way through the free ends ofthe ring and thereby become exposed at the cylinder wallwhereconsiderable damage may be done by way of scratching or scoring thecylinder wall. Insofar as I am aware, it has been heretofore thepractice of leaving the free ends of the spring removed by aconsiderable distance fromthe base of the ring groove so that frequentlyin the assembling of the rings one of the spring ends would becomepositioned between the ends of the ring and on subsequent compressionpreparatory to insertion in a cylinder a mutilation or breaking of theexpander spring .substantially entirely prevent the clogging of the oilpassage therethrough by the accumulation of carbon deposits on the ring.The ring is provided around the outer periphery 36 with a relativelywide channel 31 which defines at the upper and lower portions of theperiphery a pair of axially spaced annular portions or shoulders 38 and39 which provide for an efficient wiping'of the oil off from thecylinder side wall and at the same time the size of the channel 31affords an abundant oil capacity for the transfer-of oil onto and theremoval of oil from the cylinder side wall. 'Ihe oil is afforded passagefrom the channel 31 into the ring groove 9 and vice versa by way of aplurality of slots 4| which are formed in the ring in circumferentiallyspaced relation around the ring. The tapered sides 23 and 24 on theinner face I4 of the ring, in accordance with the present invention,extend from adjacent the top and` bottom sides 42 and 43 of the ring atthe inner periphery thereof to the slots 4| at a position spaced asubstantial distance from the inner periphery of the ring. Thus, thesmallness of the transverse o r radial dimension of the narrow portionof the slots is materially reduced and on the other hand,

the widening of the slots at the sides 23 and 24 very materiallyenlarges the oil passage with the result that there is little or noopportunity for carbon deposits to-build up in the oil passage throughthe ring and obstruct or close oi the oil flow. It will also be notedthat the extension of the sides 23 and 24 from the inner periphery ofthe ring, in no way interferes with the full radial Width of the sides42 and 43 of the ring and leaves a full and efiicient engagement ofthese sides with the ring lands 2| and 22.

Passage of oil from the ring grooves 9 into the interior 44 of thepiston is provided by way of a plurality of circumferentially spacedopenings 46 formed through the piston Wall 41 at the base of each of thering grooves supporting an oil ring.4

I claim:

1. In combination, apiston provided with an annular ring groove, apiston ring mounted in said groove, a fiat polygonal spring mountedbetween and engaged with the base of said groove and the inner face ofsaid ring for expanding said ring in said groove, said groove base andsaid inner ring face being receded from each other so as to engage saidspring exclusively at the side edges of said spring.

2. In combination, a piston having an annular ring groove, a piston ringmounted in said groove, and a fiat sinuous spring mounted between andengaged with the base of said groove and the inner face'of saidkring,said groove base and said ring face being provided with radially opposedtapered recesses receding from each other to engage said springexclusively at the side edges thereof.

3. A piston provided with a ring groove adapted for receipt of a pistonring, and a flat sinuous spring engageable between the base of saidgroove and the inner facevof said ring for expanding the latter, saidgroove base being provided with a recess receding from said groove so asto engage the sides of said recess exclusively with the side edges ofsaid spring.

4. A piston provided with a ring groove adapted for receipt of a pistonring, and a flat sinuous spring engageable between the base of saidgroove and the inner face of said ring for expanding the latter, saidgroove base being provided with a recess receding from said groove andprovided with radial inwardly tapering sides adapted for engagement1with said spring exclusively at the side edges of said spring.

5. An expansion spring for positioning between the base of al pistonring groove and the inner face of the piston ring for expanding thelatter and comprising a iiat annular sinuous member provided with spacedradial inward projections extending from the at body of said memberadjacent the inwardly disposed sinuous portions of the member andradially outward projections adjacent the outwardly disposed sinuousportions of the member adapted for engagement with said groove base andsaid ring face respectively to space the flat body of the member fromthe piston and the ring.

6. A flat polygonal expansion spring for positioning between the base ofa piston ring groove,

v and the inner face of a piston ring mounted 'in said groove forexpanding said ring, and having projections outwardly extended from theside edges thereof at the corners of the spring for' engagement withsaid groove base, and having projections inwardly extended from the sideedges along the sides of the ring intermediate said corners forengagement with the inner face of said ring.

` CHARLES F. JOHNSTON.

